The environment inside articles of footwear such as, for example, shoes, provides favorable conditions for the growth of infectious biological microorganisms, allowing bacteria, viruses, fungi, and other associated odors to proliferate. For example, foot perspiration within shoes promotes warmth and dampness. The excessive levels of harmful microorganisms sustained in enclosed shoes may cause or promote various foot maladies. It is well known that exposure to ultraviolet (UV) light of certain wavelengths, intensities, and durations can destroy or inhibit growth of surface pathogens. One approach to treating a shoe includes disinfecting the shoe with UV light generated from UV light emitting diodes (LEDs) that are mounted over an inside of a hollow shoe tree that is inserted into the toe of the shoe. UV LEDs that emit light within a germicidal range can be used to destroy microorganisms residing in the shoe. Another approach includes using an alternative light source such as a UV germicidal bulb in place of the UV LEDs. A third approach includes using visible light LEDs or a visible light source, both of which are less expensive and easier to acquire than a UV germicidal light source. Visible light LEDs or visible light bulbs can be used because light within the visible spectrum inhibits or prevents further growth of microorganisms as opposed to actually killing them. Another approach which is suitable for commercial purposes, relies on using an enclosure to contain UV light emanating from a bulb inserted inside a shoe without the support of a shoe tree.
All of the aforementioned approaches can be implemented with safeguards to contain the UV radiation exposure within a region of interest. For example, an opaque or a translucent barrier can be placed between the propagation path of the UV radiation and any openings in the shoe. One type of a barrier is a seal set around the spine or heel of a shoe tree that is placed in the shoe. Another barrier includes a light restrictor or caps incorporated in the forepart of a shoe tree that are placed over any openings in the shoe. Another approach of preventing unwanted UV exposure entails activating the UV light source only if a threshold level of ambient light is not detected. Ambient light detected inside a shoe indicates a light leak, which could allow UV radiation to escape. A light leak could be the result of improper insertion of the UV light source into the shoe. Disabling the UV light source when a threshold level of ambient light is detected by a light sensor, such as a photodiode or a phototransistor, prevents unwanted UV exposure.